Method of forming hollow staybolts



J. A. FRAUENHEIM.

METHOD OF FORMING HOLLOW STAYBOLTS.

APPLICATION FILED MAYsl. 1918 1,331,147. Patentdfeb. 17,1920.

UNITED STATES PATENT OFFICE.

JOSEPH A. FRAUENI-IEIM, 0F ZELIENOPLE, PENNSYLVANIA, ASSIGNOR T0 AMERICAN FLEXIBLE BOLT COMPANY, OF PITTSBURGH, PENNSYLVANIA, A CORPORATDN OF PENNSYLVANIA.

-METI-IOD OF FORMING HOLLOW STAYBOLTS.

Application filed May 31, 1918.

provided with a core-forming filling;

Figs. 2 and 3 are plan views of one end portion ofthe blank after it has been acted upon by one of the roll passes, the two views being taken at an angle of 90 to each other;

Figs. '4 and 5 are sections taken, respectively; on the lines IVIV and VV of Figs. 2 and.3;

Fig. 6 is a longitudinal section. of the blank after it has been acted upon by both roll passes;

Fig. 7 is a longitudinal sectional view of aportion of the rolls showing the form of the passes; and

Fig. 8 is a transverse vertical section through the rolls.

y invention has relation to the manufacture of hollow bolts. and more particularlv to stayrbolts in which the intermediate or body portion of the bolt is of smaller diameter than the head portions. The manufacture of such bolts has heretofore b en matter of considerable difiiculty. The formation of the central opening through such bolts bv boring or drilling is a diflicult and expensiveoperation; and the attempt to form the bolts over a mandrel is also not practicable with small sizes because of the slender character of the mandrel wh ch must be employed.

My invention is designed to overcome these ditliculties and to provide a simple, practical and comparatively inexpensive method by which such bolts may be manufactured.

In carrying out my invention, I provide a blank of general cylindrical form and of approximately the same diameter throughout its length, as indicated/at 2 in Fig. 1.

- This blank is provided with a central open- Specification of Letters Patent.

.the rolls. bevel entrance and exit portions 12. whereby Patented Feb. 17, 1920.

Serial No. 237,407.

ing 3, extending longitudinally therethrough. The blank is shorter than the length of the bolt to be formed therefrom and the internal bore is of a larger diameter than that which it is desired to have in the body portion of the finished bolt, being of such a size that it can be readily bored or drilled, particularly in View of the relatively short length of the blank.

The hollow blank thus formed is provided with a core of some loose or granular heatresisting material, such as refractory sand, and which may be retained in place by suitable plugs, such as indicated at 4. The intermediate or body-forming portion of the bolt is then subjected to reducing operations which elongate this portion of the blank without changing the diameter of its end or head-forming portions. While these reducing operations may be carried out by form having the portions 8 which are.

adapted to partially shape the part of the blank upon which they act to cylindrical form. The pass 9 is of approximately circular form.

The blank as shown in Fig. 1. after being brought to a suitable heat. is placed between the rolls in the manner shown in Fig. 8. be-

ing preferably grasped by a suitable pair of tongs or pincers 10. which are engaged with a suitable stop 11. so as to insure the proper initial position of the blank with respect to The roll passes are provided with as they act upon the blank. the reducedrentral portion of the blank will join the unreduced 'ends or heads hv the tapered frustoconical portions 13. The pass 8 acts to elongate the body-forming portion of the blank 'to the desired degree and at the same time partially shape it to cylindrical form. Owing to the. elli tical side portions of the pass,

however, the reduced portion of the blank is somewhat elliptical in cross section, and the result of this ellipticity is to form on each of the tapered portions- 13 oppositely pro'ecting lips or ridges 14, such as shown in igs. 2 and 4. These are of considerable importance and are purposely provided, since when the blank is turned 90 and inserted into the second pass 9 these lips or ridges insure a sure initial bite for the rolls. As a resultof this, the rolls will begin to act upon and leavethe blank-- at substantially the exact' desired points,-thereby enabling the reduced portion to be symmetrically and perfectly formed. Without these biting ridges or lips,

there is a tendency for the rolls to slip in Owing to the pliable nature of the sand I core, the sand will readily flow in the core under the reducing and elongating action of the rolls, so. that the internal'bore or openin the blank may be reduced in'diameter to substantially the same 'extent as the reduction in the external diameter of this portion of the blank.

After the blank is taken from the last roll pass, the core-forming material may be removed therefrom and the unreduced end portions threaded in any usual manner.

M invention also may be used in reclaiming bolts which are defective by reason of imperfect threads. .The end portlons of such bolts can be turned down and the resultant article used as an initial blank for the formation of a smaller sized bolt by the described method. I

The advantages of my invention will be apparent, since it provides a simple and ent1rely practicable method by which hollow bolts of this character can be rapidly made at a relatively small cost.

I do 'not claim herein broadly the method of rolling which is shown and described, as this forms the subject matter of my copending application, Serial No. 237,405 filed May 31,1918.

. I claim:

1. The method of forming hollow bolts,

a longitudinal bore therein, said blank be-. ing of a length less than that of the bolt to be formed therefrom, filling the bore of the blank with a refractory granular core-formng material, and then subjecting the inter mediate body-forming portion only of the blank to a reducing operation to elongate said portion and reduce its diameter relatively to that of the end portions of the bla substantially as described.

' 2. The method of forming hollow stay bolts, which comprisesproviding a longi-' tudinally bored blank of cylindrical form and of approximately the same cross section throughout its length, the length of,

said blank being less than that ofthe bolt to be formed therefrom, and the blank having a longitudinal bore therein, filling the bore of the blank with a refractory anular core-forming material, and then su 'jecting' the body-forming portion of the blank to a roll-reducing operation to elongate said portion and reduce its diameter relatively to that of the end portions of the blank, substantially as described.

3. In the method of forming hollow stay bolts, the steps which comprises providing a longitudinall bored blank of cylindrical form and o substantially the same cross sectionthroughout its length, said blank bein of a length greater than that of the bolt to e formed therefrom, filling the'bore of the blank with a refractory granular coreforming material, subjecting the intermediate or body-forming portion of the blank only to the action of a roll pass to reduce and elongate said portion of the blank and parwhich comprises providing a blank havlng tially shape it to cylindrical form, then turning the blank approximately 90 and subjecting it to the action of a second roll-pass to shape the reduced portion to cylindrical form, and then threading the unreduced end portions of the blank, substantially as described.

In testimony whereof I have hereunto set my hand.

- JOSEPH A. FRAUE NlTEI M. 

